How Ancient Mechanics Thought About Machines

friedo writes "The NYTimes has an interesting piece about Prof. Mark Schiefsky, a Harvard classicist with an interest in the history of science. Schiefsky pores over ancient texts in Greek, Latin, and Arabic to decipher the origin of knowledge that's been taken for granted for millennia. For example, a Greek treatise published a generation before Archimedes' proofs of the lever laws explains why, if you were a galley slave, you'd want to work the oars near the center of the ship instead of closer to the hull."

Comments

Oh, the irony!

[Chris Burke]

"For example, a Greek treatise published a generation before Archimedes' proofs of the lever laws explains why, if you were a galley slave, you'd want to work the oars near the center of the ship instead of closer to the hull."

Not a very useful treatise since if you were a galley slave, you probably couldn't read! Oh, and they wouldn't let you off the ship to visit the library and check out the treatise anyway.

Those poor, poor galley slaves.

Re:Oh, the irony!

[mschuyler]

The galley slaves didn't need to read about it. They knew by experience. This proof was for the academics who only thought about rowing, but were not condemned to do it.

Re:Oh, the irony!

[spun]

Ah, but maybe you were an educated person taken as a prisoner of war and enslaved. Perhaps you'd already read the treatise, perhaps whilst helping prepare for said war. Then, you see, you could politely ask your overseer to let you work the inside of the oars. Being suitably impressed with your grasp of physics, they would undoubtedly let you do so.

The problem is, you would rapidly figure out that you were badly mistaken in your choice. Working the inside oar gives mechanical advantage, sure, but what does that mean? You trade distance for effort. You are literally running back and forth while the guy near the edge barely moves.

This is well documented in later times when countries actually used galley slaves instead of free citizens like the Greeks used. The Greek oarsmen worked one to an oar, and each had to be well trained and motivated to work together efficiently. All the rowing positions in Greek galleys were nearly equidistant from the fulcrum. The oars in larger Greek galleys were arranged in banks, one above the other. In Roman or Turkish galleys, oars were manned by groups of slaves, and in this case the outermost position was the most desirable as it required the least movement and effort. In Greek galleys, the most desirable position was on the uppermost bank of oars because you didn't have your face pressed into the ass of the guy above you.

Re:Oh, the irony!

[Petrushka]

You're thinking of Athens, not of Greece generally, and even Athens used slaves in its navy. Hence the social importance of the battle of Arginousai: after the battle the assembly voted to give freedom to slaves who fought in the battle.

Working conditions

[The Ancients]

For example, a Greek treatise published a generation before Archimedes' proofs of the lever laws explains why, if you were a galley slave, you'd want to work the oars near the center of the ship instead of closer to the hull."

Do you think it was mentioned in their induction pack along with their sunscreen, sunhat, and timecard?

Re:Working conditions

[elronxenu]

... and sample TPS report cover sheets.

(That's TPS as in Trireme Propulsion System)

Library of Alexandria

[Bananatree3]

Only a tiny, tiny fraction of the books and scrolls within the Library of Alexandria survived, and who knows what kind of complex science and engineering was put into those books. The day it burned the world lost the greatest knowledge resource at the time.

The History channel has a program on some of these amazingly complex ancient machines

Re:Library of Alexandria

[readin]

Only a tiny, tiny fraction of the books and scrolls within the Library of Alexandria survived, and who knows what kind of complex science and engineering was put into those books. The day it burned the world lost the greatest knowledge resource at the time.

Ever wonder how much knowledge was lost when the ancient Chinese burned all their books? http://en.wikipedia.org/wiki/To_burn_the_classics_and_to_bury_the_scholars

Re:Galley slaves had other worries...

[jtev]

Being in the center has other benifits as well. You get the first chance at the gruel, you have one side of your body not being crushed up against the other galley slaves, all sorts of goodness. And one downside as well though. You're closer to the overseer's whip. So, I guess it evens out.

And here's some good pics to illustrate the point

[spun]

http://graymonk.mu.nu/archives/2007/01/roman_navy_on_t.html

http://graymonk.mu.nu/archives/2007/01/superb_models.html

Look at the oars in all three cases. They are almost exactly the same length throughout each ship.

Other great knowlege repositories

[gmezero]

It's documented that the missionaries actively destroyed Mayan literature as being pagan works of the devil. The small scraps left hint at materials that might have touched on everything from law to stellar cartography.

Re:Galley slave would want to be toward the hull

[epine]

I have to say that NYTimes article is a spectacularly good example of bad science writing. Without halfway trying, it manages to regress conservation of energy in the mind of the lay public by 200 years.

The optimal product of force through distance ultimately depends upon build (body type). Most likely the lanky rowers will be positioned at the long end of the level arm, while the stocky people are positioned with shorter lever arms.

Since you probably aren't being fed enough, your primary risk is starvation through overwork. It wouldn't surprise me that rations were set low enough that many rowers had short careers, once they burned out their physical reserves. That was certainly the implication in Ben Hur.

Since you have to maintain cadence with the rest of the oars, your option to cheat is to catch late and release early. You can bet the guy with the whip has a keen eye for shading on stroke length (duration with blade submerged).

I've stroked an eight before. Even without being able to see anyone behind me, I had a pretty good idea who was pulling their weight and who had good form. At the elite level, I'm told everyone knows who pulled a good race.

In Primo Levi's books he talks about the hazards of being teamed up with the nearly goners: the ones who haven't got enough left to pull their share, and worse, the ones who no longer cared about life enough to slack for every extra second possible.

It would be a bit different sharing an oar than lugging railway ties in the snow with half a shirt.

Probably your best situation was to be paired up with the rookie who doesn't know his 4000 calorie work day is going to be rewarded with a 1500 calorie dinner. Until the third day when he faints and you get to pull both shares all by yourself.

http://en.wikipedia.org/wiki/Sawmill

Prior to the invention of the sawmill, boards were rived and planed, or more often sawn by two men with a whipsaw, using saddleblocks to hold the log, and a pit for the pitman who worked below. Sawing was slow, and required strong and enduring men. The topsawer had to be the stronger of the two because the saw was pulled in turn by each man, and the lower had the advantage of gravity. The topsawyer also had to guide the saw so that the board was of even thickness. This was often done by following a chalkline. I was once told a story by a great ancestor that after a few weeks, the topsaw guy became so muscular he beat the crap out of the guy below, so the roles would often reverse, but that more often than not, the muscular guys took the easy jobs, and the small guys either ended up built like pit bulls, or were short for this world.

Anyways, if I'm reincarnated on a slave galley, I'd like to have that NYTimes reporter sitting beside me on the "desirable" side with the long lever arm, to discover the bio-mechanical joys of finishing your stroke at a 45 degree abdominal recline while I dent his head with my elbow every time he slacks off.

Re:Not all slaves would be illiterate ...

[trb]

Literacy rates in the fourth century aren't known, but for Athens itself, at least, the literacy rates might have been very high.

Of course they were literate. They knew ancient Greek!

Re:Galley slave would want to be toward the hull

[icegreentea]

Completely true. A galley slave really wouldn't care. Which is why the Greek States by and large didn't use slaves. Almost all oarsmen were freemen, and they had to be somewhat professional. Athens (for example) built its wealth and its 'empire' on its navy, and thus there was a sense of pride in serving the navy. Not to mention, when you have 170 oarsmen, they have to work as a coherent team. Getting 170 slaves who really don't want to be there to work properly would be detrimental. In cases where slaves were pressed into service (in emergencies or what not) they were sometimes rewarded with freedom after serving.

Re:Galley slave would want to be toward the hull

[colinrichardday]

Oh sure, drag facts and logic into Slashdot.